someone shared some helpful information regarding CoreMIDI and also some code
for a USB device using it.
however, i don’t think that can work here.
after some preliminary testing, i’m not sure i can implement MIDI in a PCI
device.
there are header conflicts between IOKit/pci/IOPCIdevice.h and CoreMIDI/*.h
this is disappointing, but right now i’m getting header conflicts.
> Showing All Messages
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/stdlib.h:228:7:
> Functions that differ only in their return type cannot be overloaded
>
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/MacTypes.h:287:41:
> Typedef redefinition with different types ('UnsignedWide' vs 'UInt64' (aka
> 'unsigned long long'))
>
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/MacTypes.h:309:41:
> Typedef redefinition with different types ('unsigned char' vs 'bool')
>
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/MacTypes.h:596:9:
> Unknown type name 'wide'
>
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/MacTypes.h:689:9:
> Unknown type name 'wide'
>
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/MacTypes.h:708:1:
> Conflicting types for 'Debugger'
relevant includes are:
> #include <IOKit/pci/IOPCIDevice.h>
> #include <CoreMIDI/MIDIServices.h>
> #include <IOKit/audio/IOAudioControl.h>
> #include <IOKit/audio/IOAudioLevelControl.h>
> #include <IOKit/audio/IOAudioToggleControl.h>
> #include <IOKit/audio/IOAudioDefines.h>
> #include <IOKit/audio/IOAudioPort.h>
i recall getting this kind of error early-on (with other headers) but obviously
it got resolved. i’m hoping there is something similar i can do this time.
i don’t know if it’d be possible to communicate with the CFBundle in an
interrupt context the way apple is suggesting.
i am thinking CoreMIDIServer.h is what i need, but unsurprisingly there is no
header in the frameworks directory.
i’ll keep you guys updated, but there has to be a way around this. of course
apple would make it difficult given their direction in the past 2+ years.
midi in a pci audio device is too obvious of a “need”
Thanks,
Gagan
> On Dec 11, 2022, at 7:08 AM, Gagan Sidhu via Coreaudio-api
> <[email protected]> wrote:
>
> hi again all,
>
> before i begin my testing, i wanted to ask about handling rudimentary MIDI
> calls.
>
> the documentation reads:
>
>> "Note: MIDI device drivers are not I/O Kit drivers. The MIDI device driver
>> model is based on the CFPlugIn architecture and typically loads a CFPlugIn
>> bundle from /System/Library/Extensions or Library/Audio/MIDI Drivers.
>>
>> For MIDI devices that cannot be directly addressed from a user-space device
>> driver (for example, a MIDI interface built into a PCI card), you must split
>> your driver into two parts: an I/O Kit device driver that matches against
>> the device and a CFPlugIn bundle that manipulates the I/O Kit driver using a
>> user client.”
>
> (https://developer.apple.com/library/archive/documentation/DeviceDrivers/Conceptual/WritingAudioDrivers/AudioOnMacOSX/AudioOnMacOSX.html#//apple_ref/doc/uid/TP30000730-TPXREF103)
>
> this is exactly the case i’m trying to handle, but i’m not sure if a
> PCIAudioDevice driver is considered user-space or not.
> -this may sound like a noobish confession, but i understand this line
> is drawn differently for BSD and Linux, and i don’t know where exactly it was
> at the time these docs were writen.
> -i do know that the newer (bad) SampleIOAudioDevice (from
> wwdc21) driver highlights being more “user-space”, so maybe a driver written
> for IOKit is considered “kernel space”
>
> anyways, i have a MIDI device that should be accessible within the device
> driver, as Clemens does here with the creation of am MPU401 device:
>
> https://elixir.bootlin.com/linux/v4.14.298/source/sound/pci/oxygen/oxygen_lib.c#L702
>
> i have googled around the terms “ioaudiodevice” and midi, only to find
> nothing.
>
> the OS-X and Kernel Programming book by halvorson and clarke says:
>
> "Core MIDI / MIDI Server framework contains APIs for working MIDI.”
>
> i was hoping one of the readers could point me to some documentation that may
> be helpful on this topic. i am hopeful the midi/uart interface can be dealt
> with inside the driver.
>
> and if it can’t, i am hoping this bundle i’d need to write wouldn’t be that
> bad. but i already have all of the uart stuff put in the right spot, so it’s
> just a matter of having a way to handle a uart interrupt on the workloop for
> a midi device.
>
> see the interrupt handling for the driver here:
> https://elixir.bootlin.com/linux/v4.14.298/source/sound/pci/oxygen/oxygen_lib.c#L117
>
>
> i just converted this function to the IOWorkLoop-equivalent.
>
>
> Thanks,
> Gagan
>
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